Cisco 4000 Series Integrated Services Routers - Cisco
Cisco ISR 4000 Series routers Comparison Chart : Simple and Quick to choose ( 50 Mbps till 2 Gbps WAN Speed ) - Route XP Private Network Services
Hardware Installation Guide for Cisco 4000 Series Integrated Services Routers - Overview of the Cisco 4000 Series ISRs [Cisco 4000 Series Integrated Services Routers] - Cisco